Tube mill

ABSTRACT

A grinding mill for grinding a material charge comprising in combination, at least one grinding chamber, a lining of wearresistant non-metallic resilient material, lifting means in the chamber for lifting and cascading material to be ground, and a plurality of spaced ring-shaped partitions within the chamber and configured to increase the lifting action exerted by the mill on the material charge.

States int 91 Enltegaard et a1,

[ TUBE MILL [75] Inventors: Torben Enkegaard; Helge Carl Christian Kartman, both of Copenhagen Valby, Denmark [73] Assignee: F. L. Smidth & Co., Cresskill, NJ.

[22] Filed: May 8, 1973 [21] Appl. No.: 358,686

[30] Foreign Application Priority Data May 10. 1972 [52] 11.8. C1 241/183, 241/284, 241/D1G. 2, 241/DIG. 3O

[51] Int. Cl. B02c 17/02, B020 17/22 [58] Field of Search 241/170-172, 241/179, 181-183, 284, DIG. 2, DIG. 3O

[56] References Cited UNITED STATES PATENTS 7/1919 Marcy 241/183 X 2/1954 Douglas 241/183 X Great Britain 21884/72 2,909,335 10/1959 Janelid 241/183 3,269,668 8/1966 Hall 241/182 X 3,378,209 4/1968 Crocheron 241/182 X 3,467,319 9/1969 Rampe 241/182 X 3,529,781 9/1970 Hastrup 241/181 3,586,249 6/1971 Fagerholt et a1 241/181 X FOREIGN PATENTS OR APPLICATIONS 1,810,920 3/1969 Germany 241/183 Primary Examiner-Granville Y. Custer, Jr, Assistant E.\aminerHoward N. Goldberg Attorney, Agent, or Firm-Pennie & Edmonds [57] ABSTRACT A grinding mill for grinding a material charge comprising in combination, at least one grinding chamber, a lining of wear-resistant non-metallic resilient material, lifting means in the chamber for lifting and cascading material to be ground, and a plurality of spaced ring-shaped partitions within the chamber and config ured to increase the lifting action exerted by the mill on the material charge.

9 Claims, 2 Drawing Figures TUBE MILL BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in tube mills of the type having at least one grinding chamber with a wear-resisting lining and lifter for lifting the material charge.

2. Description of the Prior Art In modern tube mills of this type it is known to use linings of a resilient non-metallic material. It has been found that such linings are superior to metallic linings even when the metallic linings are of special wearresisting steel alloys.

The wear-resisting non-metallic linings of the type disclosed may have either a smooth or a wavy surface and are frequently provided with lifters such as longitudinal bars or the like which are either formed as part of the lining or alternately, are embedded within the lining.

Although the linings of resilient non-metallic material are generally more expensive to install than the ordinary metallic linings, they have been found to have a much longer life expectancy. However, a serious drawback in such linings is that their grinding capacity, which is dependent upon their material lifting and cascading capability, is generally low as compared to the grinding capacity of the metallic linings. It is because of such drawbacks that although non-metallic linings such as rubber linings have been known for the past fifty years, they have not been as widely used as would be expected in view of their excellent wearing qualities. Linings of plastic materials, which are the result of more recent developments, also are not used as widely as their excellent wear capability might lead one to expect.

Certain improvements have been made by the provision of lifters in the linings in the form of longitudinal bars or by the provision of corrugations in the surface of the lining. While these measures have improved the performance of these resilient non-metallic linings, their efficiency nevertheless continues to be below acceptable levels, particularly when grinding mineral materials. Thus, when such linings of non-metal1ic materi als are installed in a grinding mill, the grinding capacity of the mill decreases while correspondingly, the amount of coarse material in the final product increases.

Since the lifting action of a non-metallic resilient lining is relatively low, the use of such a lining alone will generally permit a portion of the material to flow through the mill without being sufficiently lifted and cascaded by the mill lining with the result that it is insufficiently ground. This result is particularly found in slurry grinding mills as well as modern dry mills wherein a portion of the material charge in the mill collects in a pool in a fluidized condition.

SUMMARY OF THE INVENTION The present invention relates to a grinding mill for grinding a material charge which comprises a mill body having at least one grinding chamber in combination with a wear-resisting lining of non-metallic resilient material, and a plurality of substantially equidistant ringshaped partitions within the chamber. The partitions are so configured as to serve to increase the lifting action exerted by the mill lining on the mill charge, while permitting the material charge to flow longitudinally therethrough without interruption. The ring-shaped partitions serve to break this flow of material, without interrupting the transport thereof through the mill. Also, the partitions divide the grinding chamber into a number of sections and positively assist the lining in lifting and cascading the grinding bodies and the material.

In a preferred embodiment of the invention a mill lin- I ing of either a rubber or plastic material is provided with lifting means for lifting and cascading the material to be ground. Equally spaced ring-shaped partitions constructed either wholly or partially of a yielding material are provided, but these partitions are preferably constructed of the same material as the lining proper. The ring-shaped partitions are thus protected against abrasion in the same manner as the mill lining thereby eliminating the need for special attendance or maintenance as compared to that required by the lining.

In some circumstances it may be preferable to provide rigid partitions in the form of a solid core such as a metal core for example, which is covered or coated with a resilient material. With this construction the dimensions of the partitions may be advantageously kept low while retaining the aforementioned benefits of the resilient material coating.

In another embodiment a lining of rubber or plastics material may be utilized in combination with rings haped partitions constructed of a different material such as a metallic material. With such an arrangement the replacement cost of worn metallic partitions is economical in comparison to the cost of replacing the more expensive partitions of non-metallic resilient material. In consideration of the wear on the ring-shaped partitions, it may be necessary in certain circumstances to replace the partitions frequently thereby making it advantageous to utilize this embodiment of the invention.

Still, in other circumstances, where the abrasion to which the partitions of the mill are subjected by the material and grinding bodies is negligible, the wear on the ring-shaped partitions may be less important consideration.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are described hereinbelow with reference to the drawings wherein:

FIG. 1 is a cross-sectional view of the longitudinal section of the tube mill; and

FIG. 2 is an enlarged section taken on the line 2-2 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 there is shown an improved tube mill in accordance with the present invention. A mill body 1 is rotatably supported by hollow trunnions 2 and 3 in stationary bearings 6 and 7 which are mounted in the vertical support members. as shown. An inlet opening 4 is provided for feeding material to be ground in the mill and an outlet opening 5 is provided for discharging the ground material. A chute 8 directs the material charge into inlet opening 4.

The mill body has a grinding chamber 14 which is preferably substantially cylindrical as shown in FIG. 1,

having a lining 9 formed of a wear-resistant nonmetallic resilient material such as rubber or a suitable plastic material. A plurality of ring-shaped partitions 10 are positioned within the grinding chamber as shown and are attached to sole plates 11 which form integral portions of the lining. in the embodiment shown, the partitions are attached to sole plates 11 by being formed integrally therewith and the ring-shaped partitions are constructed of the same rubber or plastic material as that of the lining 9. Thus the partitions are actually embedded in the lining through the agency of the sole plates 11. The sole plates 11 may alternately be in the form of substantially cylindrical separate ring-like members attached to the partitions 10.

Referring to FIG. 2, there is shown a representative ring-shaped partition 10 which has an open work configuration with a central opening and a plurality of rectangular openings or holes 12 which are intended to allow material to be ground to pass longitudinally through the mill as the mill body is rotated. It can be seen that the configuration of the partitions 10 as shown assist the lining substantially in lifting the material upwardly in the direction of rotation of the mill thereby providing additional cascading of the material charge. The lining 9 of the mill also includes lifting bars 13 which are longitudinally positioned as shown and serve to lift and cascade the charge of material and grinding bodies in the chamber.

The mill shown in FIG. 1 has one grinding chamber 14 and a discharge chamber 15 separated from the grinding chamber by a dam ring 16 having means (not shown) for returning grinding bodies to the grinding chamber. This type of discharge furthers the formation of pools of fluidized material in the grinding chamber, particularly in a dry grinding mill of this type.

It can be seen that without the improved partitions of the present invention the pool may tend to flow too rapidly through the mill due to the low lifting capacity of the rubber or plastic lining. However, the ringshaped partitions effectively interrupt the flow and at the same time, improve the lifting capacity of the rubber or plastic lining.

A brief comparison of the grinding capacity of a mill of the type disclosed with and without partitions is set forth below. In the following chart, t represents tons of material charge, hr" represents hours, kw.hr represents kilowatt-hours, and BS. Mesh 52" represents British Standard Mesh 52 which is about equivalent to a 300 micro mesh size:

1. A grinding mill for grinding a material charge which comprises a mill body having at least one grinding chamber, a lining of wear resistant non-metallic resilient material in said grinding chamber, lifting means in said grinding chamber mounted on the resilient lining for lifting and cascading the material to be ground, and a plurality of ring shaped partitions within said chamber, said partitions being substantially equally spaced along the axis of the mill and define at least a central opening and a plurality of openings arranged in a substantially circular pattern so as to provide additional lifting action on the material charge while permitting the material to pass therethrough without interruption in a substantiallylongitudinal direction.

2. The grinding mill according to claim 1 wherein said partitions are attached to substantially cylindrically configured sole plates embedded within the lining, said partitions thereby forming an integral part of the lining.

3. The grinding mill according to claim 2 wherein the lining of said grinding chamber is made of one of a rubber and plastic material and at least a portion of each ringshaped partition is constructed of a resilient material.

4. The grinding mill according to claim 3 wherein said partitions are constructed of the same material said lining of said grinding chamber.

5. The grinding mill according to claim 4 wherein at least certain of said openings in said partitions have a substantially rectangular configuration.

6. The grinding mill according to claim 1 wherein each of said ring-shaped partitions comprises a solid core surrounded and covered with a resilient wearresistant non-metallic material.

7. The grinding mill according to claim 6 wherein the solid core of each ring-shaped partition is constructed of a metallic material.

8. The grinding mill according to claim 1 wherein the ring-shaped partitions are constructed entirely of a metal.

9. A grinding mill for grinding a material charge which comprises a mill body having at least one grinding chamber, a charge of grinding bodies, means in said grinding chamber to prevent the grinding bodies from exiting therefrom, a lining of wear resistant nonmetallic resilient material in said grinding chamber, lifting means in said grinding chamber mounted on the resilient lining for lifting and cascading the grinding bodies and the material to be ground, and a plurality of ring shaped partitions within said chamber, said partitions being substantially equally spaced along the axis of the mill and defining at least a central opening and a plurality of openings spaced from the central opening and arranged in a substantially circular pattern so as to provide additional lifting action on the material charge while permitting the material and grinding bodies to pass therethrough without interruption in a substantially longitudinal direction. 

1. A grinding mill for grinding a material charge which comprises a mill body having at least one grinding chamber, a lining of wear resistant non-metallic resilient material in said grinding chamber, lifting means in said grinding chamber mounted on the resilient lining for lifting and cascading the material to be ground, and a plurality of ring shaped partitions within said chamber, said partitions being substantially equally spaced along the axis of the mill and define at least a central opening and a plurality of openings arranged in a substantially circular pattern so as to provide additional lifting action on the material charge while permitting the material to pass therethrough without interruption in a substantially longitudinal direction.
 2. The grinding mill according to claim 1 wherein said partitions are attached to substantially cylindrically configured sole plates embedded within the lining, said partitions thereby forming an integral part of the lining.
 3. The grinding mill according to claim 2 wherein the lining of said grinding chamber is made of one of a rubber and plastic material and at least a portion of each ring-shaped partition is constructed of a resilient material.
 4. The grinding mill according to claim 3 wherein said partitions are constructed of the same material as said lining of said grinding chamber.
 5. The grinding mill according to claim 4 wherein at least certain of said openings in said partitions have a substantially rectanGular configuration.
 6. The grinding mill according to claim 1 wherein each of said ring-shaped partitions comprises a solid core surrounded and covered with a resilient wear-resistant non-metallic material.
 7. The grinding mill according to claim 6 wherein the solid core of each ring-shaped partition is constructed of a metallic material.
 8. The grinding mill according to claim 1 wherein the ring-shaped partitions are constructed entirely of a metal.
 9. A grinding mill for grinding a material charge which comprises a mill body having at least one grinding chamber, a charge of grinding bodies, means in said grinding chamber to prevent the grinding bodies from exiting therefrom, a lining of wear resistant non-metallic resilient material in said grinding chamber, lifting means in said grinding chamber mounted on the resilient lining for lifting and cascading the grinding bodies and the material to be ground, and a plurality of ring shaped partitions within said chamber, said partitions being substantially equally spaced along the axis of the mill and defining at least a central opening and a plurality of openings spaced from the central opening and arranged in a substantially circular pattern so as to provide additional lifting action on the material charge while permitting the material and grinding bodies to pass therethrough without interruption in a substantially longitudinal direction. 